I plumed one in on mine just to check I was getting the 5.5 psi. Used a small plastic T-piece (actually a windshield wipers-wash line connector!) into the MSD boost box vacuum rubber hose supply line. Then just run another rubber vacuum hose line off that, (you can buy lengths of it at Autoshops) to the back of your gauge, just pushes on, easy as that! The basic boost gauges don't even require electrics to them if you don't want it lit at night.
You can get fluid filled gages, these are good quality as the reason for the fluid is to stop any needle-pointer quiver that it can pick up off car vibrations. Problem with most boost gages is that they are for Turbos and display big boost readings, say 30 psi or several bar, and the 5 psi will hardly show on the dials low graduation markings! There are some about that display to 15 psi, so shop around. The US company I know for that does them is
www.jegs.com I think they are about $30.